Heat exchanger

Abstract

A heat exchanger includes front and back walls forming a flue gas space such that a fluid flowing through a channel formed in the front and back walls can exchange heat with flue gas in the flue gas space, in use. The front wall includes a lower portion extending along the back wall, and an upper portion extending upwardly from an upper end of the lower portion and outwardly away from the back wall to form a combustion space of a flammable gas between the upper portion and the back wall. A length of the upper portion along a longitudinal direction thereof is longer than a length of the lower portion along a longitudinal direction thereof.

The invention claimed is: 
     
       1. A heat exchanger comprising:
 a front wall; and 
 a back wall forming a flue gas space together with the front wall such that a fluid flowing through a channel formed in the front and back walls can exchange heat with flue gas in the flue gas space, in use, 
 the front wall including
 a lower portion extending along the back wall, and 
 an upper portion extending upwardly from an upper end of the lower portion and outwardly away from the back wall to form a combustion space of a flammable gas between the upper portion and the back wall, 
 a length of the upper portion along a longitudinal direction thereof is longer than a length of the lower portion along a longitudinal direction thereof, and 
 an entirety of the back wall extending upwardly along a same direction of the lower portion of the front wall. 
 
 
     
     
       2. The heat exchanger according to  claim 1 , wherein
 the upper portion of the front wall is plane shaped. 
 
     
     
       3. The heat exchanger according to  claim 2 , wherein
 the lower portion of the front wall is plane shaped. 
 
     
     
       4. The heat exchanger according to  claim 2 , wherein
 a fin and pins extending backwardly from an inner surface of the front wall are formed on the front wall, the fin having a varying thickness as measured perpendicularly relative to the back wall, 
 the pins are arranged on a downstream side of the fin with respect to a flue gas flow direction, 
 the fin and some of the pins are arranged at the upper portion, and 
 a remainder of the pins are arranged at the lower portion. 
 
     
     
       5. The heat exchanger according to  claim 1 , wherein
 the lower portion of the front wall is plane shaped. 
 
     
     
       6. The heat exchanger according to  claim 3 , wherein
 a fin and pins extending backwardly from an inner surface of the front wall are formed on the front wall, the fin having a varying thickness as measured perpendicularly relative to the back wall, 
 the pins are arranged on a downstream side of the fin with respect to a flue gas flow direction, 
 the fin and some of the pins are arranged at the upper portion, and 
 a remainder of the pins are arranged at the lower portion. 
 
     
     
       7. The heat exchanger according to  claim 1 , wherein
 a fin and pins extending backwardly from an inner surface of the front wall are formed on the front wall, the fin having a varying thickness as measured perpendicularly relative to the back wall, 
 the pins are arranged on a downstream side of the fin with respect to a flue gas flow direction, 
 the fin and some of the pins are arranged at the upper portion, and 
 a remainder of the pins are arranged at the lower portion. 
 
     
     
       8. A heat exchanger comprising:
 a front wall; and 
 a back wall forming a flue gas space together with the front wall such that a fluid flowing through a channel formed in the front and back walls can exchange heat with flue gas in the flue gas space, in use, 
 the front wall including
 a lower portion extending along the back wall, and 
 an upper portion extending upwardly from an upper end of the lower portion and outwardly away from the back wall to form a combustion space of a flammable gas between the upper portion and the back wall, 
 a length of the upper portion along a longitudinal direction thereof is longer than a length of the lower portion along a longitudinal direction thereof, 
 
 a fin and pins extending backwardly from an inner surface of the front wall being formed on the front wall, the fin having a varying thickness as measured perpendicularly relative to the back wall, 
 the pins being arranged on a downstream side of the fin with respect to a flue gas flow direction, 
 the fin and some of the pins being arranged at the upper portion, and 
 a remainder of the pins being arranged at the lower portion. 
 
     
     
       9. A heat exchanger according to  claim 8 , wherein
 each of the pins has a larger surface area per unit volume than the fin.